(1) Field of the Invention
The present invention relates to a large-sized scooter type vehicle incorporating an engine with a large displacement, and more detailedly relates to improvement of the arrangement of the fuel tank and the radiator.
(2) Description of the Prior Art
There have been various types of two-wheeled vehicles. In recent years, large-sized scooters incorporating an engine with a large displacement have drawn market attention and been developed.
As the prior art documents related to this, Japanese Patent Application Laid-Open Hei 10 No. 203460, 9 No. 11957, Japanese Patent Publication Hei 8 No. 18586 may be referred to.
The development of scooters of this type has been investigated and discussed with concern to various items. One of them is a positional relationship between the fuel tank and the radiator. The most typical method is to build in a fuel tank under the scooter seat. This method, however, requires the seat to be open when refuelling. Further, since the fuel tank is arranged close to the storage box for a helmet etc., there is a concern that the fuel may stain the helmet etc., during refuelling, unwillingly.
In view of the above point, a method has been proposed in which the fuel tank is arranged inside a tunnel formed under the step-through space of the scooter so as to allow for refuelling while the rider is seated. This method also poses a similar difficulty to the above, that is, there is a concern that rider""s shoes or clothes may be stained with the fuel because the legs will be set close to the fuel tank. Further, since the fuel tank is located at a lower position, the operator has to bend over to open and close the fuel tank cap. Moreover, if the radiator is arranged in front of the fuel tank, it is necessary to provide an air flow passage of cooling air between the fuel tank and the radiator.
The present invention has been devised in view of the above difficulties and it is therefore an object of the present invention to provide a scooter type vehicle which allows for refuelling without the necessity for the seat to be opened, is avoidable from the unwilling fuel staining, and allows the operator to open and close the fuel tank cap in an easy position.
In order to achieve the above object, the present invention is configured as follows:
In accordance with the first aspect of the present invention, a scooter type vehicle includes:
a front fork assembly having a rotatable front wheel at the lower position thereof and a handlebar at the upper position thereof;
a head pipe at the front end of the bodywork frame, rotatably supporting the front fork assembly;
part of the bodywork being bent downwards between the head pipe and a saddle, defining a step-through space; and
a low floor, step board arranged at the bottom of the step-through space, and is characterized in that a pair of left and right down tubes are downwardly and rearwardly extended from the head pipe in front of the step-through space so as to frame a fuel tank and planiform radiator, in the upper and lower positions, respectively; the fuel tank, which is arranged above the radiator, has a lower part which bulges downwards over the upper edge of the radiator and toward the rear space of the radiator located below the fuel tank; and the forward face of the bulge portion, opposing the rear face of radiator is adapted to be inclined rearward and downward.
In accordance with the second aspect of the present invention, the scooter type vehicle having the above first feature further includes:
an engine and transmission integrally formed into an engine unit;
an engine case portion which integrally incorporates the crankshaft of the engine unit and the transmission and is arranged under the saddle;
a cylinder portion projected forwards in an approximately horizontal direction from the engine case portion; and
a tunnel structure forming an engine tunnel, which is extended fore and aft and ridged upward in the step-through space around the center of the step board with respect to the left and right direction thereof, and is characterized in that the cylinder portion is arranged inside the engine tunnel while a spark plug provided on top of the cylinder head is arranged with its fastening axis aligned to the direction toward the downwardness of the fuel tank.
In accordance with the third aspect of the present invention, the scooter type vehicle having the above first feature is characterized in that the radiator arranged below the fuel tank in the rear of the front wheel is attached to the bodywork so as to be inclined with its lower portion directed forward.
In accordance with the fourth aspect of the present invention, the scooter type vehicle having the above second feature is characterized in that the radiator arranged below the fuel tank in the rear of the front wheel is attached to the bodywork so as to be inclined with its lower portion directed forward.
Here, the engine portion of the engine unit of the present invention is not particularly limited, and may include various types such as a parallel two-cylinder engine, parallel three-cylinder engine, V-type two-cylinder engine, V-type four-cylinder engine and horizontal opposed type two cylinder.
According to the above first configuration of the present invention, since the fuel tank is arranged at a high position in the step-through space, separately from the saddle, refuelling can be performed without opening and closing the saddle. Further, it is possible for the operator to open and close the cap of the fuel tank, in their relatively conformable position. Since the fuel tank is disposed away from the storage box or rider""s legs, there is little concern that the fuel might unwillingly stain rider""s shoes, clothes etc.
According to the above second configuration of the present invention, it is possible to improve the cooling efficiency of the spark plug arranged in the cylinder head of the cylinder as a part of the engine.
According to the above third or fourth configuration of the present invention, since the radiator can be directed as perpendicularly to the air flow as possible, it is possible to reduce the resistance and improve the cooling efficiency.